Process and device for triggering and/or carrying out chemical reactions

ABSTRACT

In a process for triggering and/or carrying out chemical reactions by irradiating starting materials and, in particular, liquid starting materials with short-wave electromagnetic radiation emitted from at least one substance sending out short-wave electromagnetic radiation upon irradiation and excitation with long-wave electromagnetic radiation under operating conditions, the short-wave electromagnetic radiation is generated in a closed vessel arranged within the starting materials and containing the short-wave electromagnetic radiation emitting substance. A device for triggering and/or carrying out chemical reactions by irradiating with short-wave electromagnetic radiation starting materials and, in particular, liquid starting materials received in a receptacle, includes a generator for generating long-wave electromagnetic radiation as well as a vessel for receiving at least one substance sending out short-wave electromagnetic radiation upon irradiation and excitation with long-wave electromagnetic radiation under operating conditions. It is provided that the receptacle for the starting materials is designed to be permeable to long-wave electromagnetic radiation. The vessel receiving the short-wave electromagnetic radiation emitting substance, furthermore, is arranged within the receptacle and at least partially surrounded by the starting materials.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a process for triggering and/orcarrying out chemical reactions by irradiating starting materials and,in particular, liquid, or mixtures of liquid and solid, startingmaterials with short-wave electromagnetic radiation emitted from atleast one substance sending out short-wave electromagnetic radiationupon irradiation and excitation with long-wave electromagnetic radiationunder operating conditions, as well as a device for triggering and/orcarrying out chemical reactions by irradiating with short-waveelectromagnetic radiation starting materials and, in particular liquid,or liquid and solid, starting materials received in a receptacle,comprising a generator for generating long-wave electromagneticradiation as well as a vessel for receiving at least one substanceemitting short-wave electromagnetic radiation upon irradation andexcitation with long-wave electromagnetic radiation under operatingconditions.

2. Prior Art

The realization of chemical reactions or processes by irradiation hasbeen known for long with the most diverse effects being obtainable as afunction of the substances used and the radiations applied. In thiscontext, it is known to initiate or promote chemical processes byirradiation with long-wave electromagnetic waves such as, for instance,microwaves or with short-wave electromagnetic waves such as ultravioletwaves. Thus, it is known that it is possible by means of ultravioletradiation to kill germs in food and luxury food or in biologicmaterials, thereby sterilizing such materials without having to applyelevated temperatures. Moreover, it is feasible to start, or keep going,specific reactions by excitation with electromagnetic waves in the UVrange, whereas the use of microwaves is of particular advantage inchemistry if reactions or processes are to occur at elevatedtemperatures.

In many cases, however, it is particularly the combination of bothlong-wave and short-wave electromagnetic waves which yields particularlyrapid and good results such that EP-A 0 429 814 has already proposedboth a process and a device for triggering and/or promoting chemicalprocesses, in which both long-wave electromagnetic waves, namelymicrowaves, and short-wave electromagnetic waves, namely ultravioletrays, have been employed. In that process and the pertinent arrangement,it is proceeded in a manner that a receptacle for the starting materialsto be treated and a gas reaction tube are arranged in a microwave oven,wherein the waves emitted from the microwave oven impinge on the gasreaction tube containing substances capable of being excited bymicrowaves and sending out UV rays upon excitation. The UV rays sent outby that gas reaction tube subsequently are directed onto the reactionvessel contained in the gas reaction tube or surrounded by the same andcontaining the substances or starting materials to be reacted. Thatknown configuration involves the drawback that, in particular, alarge-volume gas reaction tube having large dimensions suitable forsurrounding an accordingly large reaction vessel must be provided andthat, in particular, no uniform radiation density can be readilysafeguarded over the total volume of the reaction vessel andparticularly in its center at an accordingly large dimension of thereaction vessel. Another disadvantage of a gas reaction tube enclosingthe reaction vessel resides in that exclusively materials that aretransparent to short-wave electromagnetic radiation can be used for thereaction vessel. This constitutes a considerable limitation to the useof, in particular, pressure reaction vessels.

SUMMARY OF THE INVENTION

The present invention aims at providing a process and a device, by whichit is feasible to afford directly in the reaction mixture to be reacted,or in the starting materials, as high a density of short-wave UVradiation as possible in order to be able to provide both a specificexcitation and an accordingly augmented yield of reaction products.

To solve this object, the process according to the invention, departingfrom the initially defined prior art, is essentially characterized inthat the short-wave electromagnetic radiation is generated in a closedvessel arranged within the starting materials and containing ashort-wave electromagnetic radiation emitting substance. By emittingshort-wave electromagnetic waves in a closed vessel arranged within thestarting materials and containing the UV radiation emitting substances,an intensified UV irradiation of the reaction mixture or startingmaterials is feasible, thereby both improving and augmenting thereaction yields of the reaction excited by the electromagnetic radiationand offering the opportunity to carry out by the process according tothe invention reactions that can only be excited by electromagneticradiation of a specific wavelength.

In a preferred manner, and in order to provide an electromagneticradiation of a specific wavelength, the process according to theinvention is carried out such that a low pressure or negative-pressuregas is used as the short-wave electromagnetic radiation emittingsubstance. In order to ensure the safe ignition of the short-waveelectromagnetic wave emitting gas, the process according to theinvention preferably is conducted in a manner that ignition of the lowpressure gas is caused by effecting an additional irradiation andexcitation of a solid electrode and, in particular, a metallic electrodein the vessel receiving the low pressure gas. By providing an electrodeand, in particular, a metallic electrode in the vessel receiving the lowpressure gas or gas under subatmospheric pressure, an ignition spark isformed on the solid and, in particular, metallic electrode by thelong-wave electromagnetic radiation, which ignition spark will safelyignite the low pressure gas contained in the vessel such that short-waveelectromagnetic radiation will be continuously provided by the gasdischarge of the low pressure gas.

In a preferred manner, the process according to the invention isconducted such that noble gases, methane, CO₂ and, in particular, gasesemitting carbon bands at 193 and 247 nm are used for the low pressuregas in order to generate the short-wave electromagnetic radiation. Byusing noble gases, such as argon, methane or CO₂, as well as gasesemitting carbon bands at 193 and 247 nm, a specific excitation ofselected substances may be effected and a concerted reaction control maybe ensured.

For as broad a scattering as possible, of the short-wave electromagneticradiation to be emitted, the process according to the invention isfurther developed such that metals or metal-like substances which, underoperating conditions, form volatile substances sending out short-waveelectromagnetic radiation upon irradiation and excitation with long-waveelectromagnetic radiation are used as the short-wave electromagneticradiation emitting substance, wherein As, Bi, Cd, Cs, Ge, Hg, P, Pb, Rb,Sb, Se, Sn, Te, Tl or Zn, in particular, are used as metals ormetal-like substances. By providing metals or metal-like substanceswhich, under operating conditions, form volatile substances acting as ashort-wave electromagnetic radiation emitting substance, it is feasibleto send out the most diverse excitation energies and the most diversewavelengths of short-wave electromagnetic radiation such that aplurality of chemical reactions may be carried out by the processaccording to the invention.

By said short-wave electromagnetic radiation emitting substances beingcontained in a vessel arranged within the reaction mixture, an intensiveirradiation of the reaction mixture or starting materials is, moreover,safeguarded such that not only a plurality of reactions may be carriedby the process according to the invention, but also elevated yields ofreaction products may be guaranteed.

In order to be able to simultaneously emit a plurality of differentwavelengths of short-wave electromagnetic radiations, the processaccording to the invention preferably is conducted in a manner that amixture of at least one low pressure gas and/or at least one metal ormetal-like substance is used as the short-wave electromagnetic radiationemitting substance. By providing a combination of a low pressure ornegative-pressure gas and at least one metal or metal-like substance, abroader spectrum of UV bands or wave ranges can be made available, thusalso ensuring the excitation of complex reaction mixtures or thepromotion and maintenance of rather complex reactions.

According to the invention, microwaves are preferably used as long-waveelectromagnetic radiations employed for exciting the substance(s)emitting short-wave electromagnetic radiations.

According to the invention UV rays are preferably applied as short-waveelectromagnetic radiation used for exciting reaction mixtures orstarting materials, since in the UV range a relatively large number ofsubstances or reaction mixtures can be excited and a plurality ofreactions can be promoted.

The processes or methods according to the invention preferably arecarried out at temperatures ranging from room temperature to about 400°C. and, in particular, between 100° C. and 300° C. The process controlaccording to the invention enables a reaction to be conducted both atroom temperature and at elevated temperatures, wherein elevatedtemperatures may be produced directly by the long-wave electromagneticradiation and, in particular, microwaves, thus enabling both theadvantage of heating the reaction mixture and the excitation of the gasdischarge of the UV radiator in one operating step.

By realizing the process with the vessel containing the short-waveelectromagnetic radiation emitting substance being arranged in theinterior of the starting materials, the chemical process(es) preferablymay be carried out under a pressure ranging from atmospheric pressure toapproximately 200 bars. In particular, the realization of reactionsunder elevated pressure is feasible only by arranging the vesselcontaining the short-wave electromagnetic radiation emitting substancein the interior of the reaction mixture, since short-waveelectromagnetic radiation often cannot penetrate high-pressure vesselssuch that reactions under elevated pressures in the hitherto knownprocesses have been feasible not at all or only with difficulty.

In order to solve the above-defined object, a device according to theinvention for triggering and/or carrying out chemical reactions byirradiating with short-wave electromagnetic radiation starting materialsand, in particular, liquid, or liquid and solid, starting materialsreceived in a receptacle, comprising a generator for generatinglong-wave electromagnetic radiation as well as a vessel for receiving atleast one substance sending out short-wave electromagnetic radiationupon irradation and excitation with long-wave electromagnetic radiationunder operating conditions is essentially characterized in that thereceptacle for the starting materials is designed to be permeable tolong-wave electromagnetic radiation and the vessel receiving theshort-wave electromagnetic radiation emitting substance is arrangedwithin the receptacle and at least partially surrounded by the startingmaterials. Due to the vessel receiving the short-wave electromagneticradiation emitting substance being arranged within the receptacle and atleast partially surrounded by the starting materials, it is feasible bymeans of the device according to the invention to ensure intensiveirradiation of the reaction mixture with the short-wave electromagneticradiation so as to safeguard an elevated reaction speed and enhancedyields of the chemical reaction intended to be carried out in thereceptacle.

In order to ensure as intense an irradiation as possible as well as ahigh radiation efficiency of the short-wave radiation emittingsubstance, the invention preferably is further developed such that thevessel receiving the short-wave electromagnetic radiation emittingsubstance is formed by a closed, substantially tubular vessel. Byproviding a closed substantially tubular vessel which is at leastpartially embedded in the reaction mixture, a largely uniformirradiation of the substances to be reacted, with the short-waveelectromagnetic radiation is feasible such that starting materialscontained in the receptacle can be completely reacted or excited withinthe shortest time possible without requiring additional whirling orstirring.

In order to ensure as complete a penetration as possible of theshort-wave electromagnetic radiation through the vessel provided for thesubstance emitting such radiation and to optimize the radiationefficiency, the device according to the invention is further developedsuch that the vessel receiving the short-wave electromagnetic radiationemitting substance is made of quartz glass or UV-transparent aluminumoxide compounds and, in particular, sapphire.

In order to ensure the ignition of the gas discharge and its uniformoperation in the interior of the vessel receiving the short-waveelectromagnetic radiation emitting substance and as intense a UVradiation emission as possible, the device according to the invention isfurther developed such that said vessel comprises an additional ignitionmeans, particularly an electrode.

In order to safely render feasible the excitation of the short-waveelectromagnetic radiation emitting substance by aid of the long-waveelectromagnetic radiation and not to exceed the radiation amount oflong-wave electromagnetic radiation required for the excitation of theshort-wave electromagnetic radiation, it is preferred that thereceptacle for the starting materials is made of SiO₂, a plasticstransparent to long-wave electromagnetic radiation such as, forinstance, PTFE, TFM, PFA, or aluminum oxide compounds. By making thereceptacle of a plastics transparent to long-wave electromagneticradiation, SiO₂ or aluminum oxide compounds, it is feasible to passthrough the receptable the long-wave electromagnetic radiationsubstantially unfiltered and without being attenuated by the receptacleso as to enable the excitation of the gas discharge without excessiveenergy input.

In order to be able to carry out in the interior of the receptable alsoreactions at elevated pressures or elevated temperatures, the receptaclefor the starting materials according to the invention is formed by adouble-walled container provided with a pressure-tight closure. In orderto be able to monitor the course of a reaction and reapportion startingmaterials in the course of the reaction, the receptacle may beconfigured such that the closure is provided with a separately closeableopening, in particular for taking samples and/or apportioning startingmaterials.

In order to be able to carry out in the receptacle for the startingmaterials reactions at elevated temperatures either under normalpressure or at an elevated pressure, the receptacle for the startingmaterials is either enclosed on all sides by a long-wave electromagneticradiation producing generator comprised of a microwave oven orunilaterally irradiated by microwaves focussed by means of a hollowwaveguide or similar means known in microwave technology. The receptacleconsequently is within a field of long-wave electromagnetic radiationand, in particular, a microwave field. The microwaves may be supplied tothe receptacle for the starting materials either focussed via a resonantcavity or diffused by a “multimode cavity” (e.g., microwave oven),thereby heating the reaction mixture to the desired temperature anddeveloping the gas discharge in the interior of the vessel receiving theshort-wave electromagnetic radiation emitting substance.

BRIEF DESCRIPTION OF THE DRAWINGS

In the following, the invention will be explained in more detail by wayof exemplary embodiments schematically represented in the annexeddrawing. Therein:

FIG. 1 is a partially sectioned view of a device according to theinvention for carrying out the process according to the invention,comprising a reception container in whose interior another container forreceiving a short-wave electromagnetic radiation emitting substance isarranged;

FIG. 2 is a schematic side view of a modified embodiment of a deviceaccording to the invention with a means for excitation with long-waveelectromagnetic radiation, in particular microwaves, being schematicallyillustrated in addition;

FIG. 3 is a partially sectioned view through another embodiment of thedevice according to the invention with the receptacle for the startingmaterials to be reacted being positioned within a pressure vessel; and

FIG. 4 is a further schematic sectional view through a device accordingto the invention, in which the pressure vessel of FIG. 3 is arranged ina usual microwave oven schematically illustrated.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS OF THE INVENTION

FIG. 1 depicts a receptacle generally denoted by 1 and charged withstarting materials or chemical substances to be reacted, which areschematically indicated by 2. The receptacle 1 is made of a materialpermeable to long-wave electromagnetic radiation and, in particular, amaterial permeable to microwaves, such as SiO₂, microwave-permeableplastics or special aluminum oxides. In the interior of the receptacle1, and partially immersed in the reaction mixture or starting materials2, there is arranged a gas-tightly closed vessel 3 in whose interior iscontained the short-wave electromagnetic radiation emitting substance,such as a noble gas, or substances emitting UV radiation under operatingconditions, such as metals or metal compounds, which are schematicallyindicated by 4 in FIG. 1. In the operating state, long-waveelectromagnetic radiation 5 emitted from a generator not illustratedand, in particular, comprised of microwaves impinges on the receptacle1, penetrating the latter on account of the materials selected for theopen container 1 and likewise being able to pass through the vessel 3for the short-wave electromagnetic radiation emitting substance arrangedin the interior of the receptacle 1. The vessel 3 in the instant case ispermeable not only to long-wave electromagnetic radiation 5, but also toUV or short-wave electromagnetic radiation 6 sent out in its interior.By the long-wave electromagnetic radiation 5 passing through thereceptacle 1 and the vessel 3, the substance contained in the interiorof vessel 3 is excited to emit short-wave electromagnetic radiation 6,which after passing through the wall of the vessel 3 directly impingeson the reaction mixture 2, thereby ensuring particularly intense UVirradiation of the reaction mixture or starting materials 2. Any shapeand any number of receptacles 1 arranged in the arrangement forexcitation by long-wave electromagnetic radiation 5 not illustrated maybe envisaged, since the excitation of the reaction mixture 2 merely isdetermined by the substances contained in the vessel 3 and the UV raysemitted from the same.

FIG. 2 again depicts a receptacle denoted by 1 in a schematicallyillustrated arrangement intended to emit long-wave electromagneticradiation 5 and, in particular, microwaves. In that arrangement, agenerator 7, in particular a magnetron, sends out microwaves 5 which,focussed by a hollow waveguide, after passage through the receptacle 1and vessel 3 excite the substance contained in the interior of thevessel 3 to emit short-wave electromagnetic radiation 6. The receptacle1 is arranged in an open sleeve 8, the system according to FIG. 2 beingintended for operation under normal pressure. The arrangement accordingto FIG. 2 allows for operation at temperatures ranging between roomtemperature and the boiling temperature of the reaction mixture.

FIG. 3 represents another sectional view of a receptacle 1 for receivingchemical reaction mixtures 2 with the reference numerals of FIG. 1having been taken over into the illustration according to FIG. 3unchanged. In the interior of the reaction mixture 2 there is againprovided a vessel 3, which contains substances 4 capable of beingexcited by long-wave electromagnetic radiation 5, which, uponexcitation, emit the short-wave electromagnetic radiations schematicallyindicated by 6, in particular UV radiations. In order to ensure the safeexcitation of the substances 4 contained within the vessel 3 and assistin their ignition, the vessel 3 is equipped with an ignition electrode9, in particular a metallic ignition electrode, which, upon excitationwith long-wave electromagnetic radiation 5 is capable of igniting, andhence exciting to send out UV rays 6, the substances 4 contained in thevessel 3. The receptacle 1 according to FIG. 3, furthermore, issurrounded by a second container 10 made of a material permeable tolong-wave electromagnetic radiation 5 and configured so as to besuitable also for reactions proceeding under elevated pressure in thereceptacle 1. The additional container 10 is provided with aschematically indicated pressure-tight closure 11 such that, by thedevice according to FIG. 3, reactions not only at elevated temperaturesbut also at elevated pressures may be carried out, which at the sametime require excitation by short-wave electromagnetic radiation 6 and,in particular, UV radiation in order to be carried out. In order todrain any inadmissible reaction pressure from the receptacle 1, abursting disc 12 is provided in the lid 13 and the lid 13 is pressed onthe receptacle 1 by a spring so that the lid will be opened by excesspressure.

Reactions with containers according to FIG. 3 usually are carried out incurrent microwave ovens as illustrated in FIG. 4, the oven in FIG. 4being schematically indicated by 14.

Due to the excitation of a reaction mixture 2 by means of vessels 3directly arranged within the reaction mixture 2 and containingsubstances 4 suitable for sending out UV radiation or short-waveelectromagnetic radiation 6, such as noble gases or metal compoundsvolatile under operating conditions and emitting UV bands, as providedby the invention, it is feasible to afford directly in the reactionmixture or starting materials 2 a particularly high radiation density ofshort-wave radiation and, in particular, UV rays 6, thus ensuring asrapid as possible and, in particular, as complete as possible thereaction of the reaction mixture 2 at any desired operating conditions.The gas discharge in the interior of the vessel 3 causes the microwaveradiation 5 to be focussed on the reaction mixture 2 within thereceptacle 1 and on the vessel 3 containing the UV radiation emittingsubstances 4.

What is claimed is:
 1. A process for triggering and/or carrying outchemical reactions by irradiating starting materials with short-waveelectromagnetic radiation emitted from at least one substance sendingout short-wave electromagnetic radiation upon irradiation and excitationwith long-wave electromagnetic radiation under operating conditions,said starting materials being placed in a receptacle, said receptacleallowing long-wave electromagnetic radiation to pass therethrough whilepreventing penetration of short-wave electromagnetic radiation, theshort-wave electromagnetic radiation being generated in a closed vesselarranged within the starting materials and containing the short-waveelectromagnetic radiation emitting substance.
 2. A process according toclaim 1, wherein a low pressure gas is used as the short-waveelectromagnetic radiation emitting substance.
 3. A process according toclaim 2, wherein ignition of the low pressure gas is caused by effectingan additional irradiation and excitation of a solid electrode in theclosed vessel receiving the low pressure gas.
 4. A process according toclaim 2, wherein noble gases, methane, CO₂ and gases emitting carbonbands at 193 and 247 nm are used for the low pressure gas in order togenerate the short-wave electromagnetic radiation.
 5. A processaccording to claim 1, wherein metallic substances which, under saidoperating conditions, form volatile substances sending out saidshort-wave electromagnetic radiation upon irradiation and excitationwith said long-wave electromagnetic radiation are used as the short-waveelectromagnetic radiation emitting substance.
 6. A process according toclaim 5, wherein As, Bi, Cd, Cs, Ge, Hg, P, Pb, Rb, Sb, Se, Sn, Te, Tlor Zn are used as the substances.
 7. A process according to claim 1,wherein a mixture of at least one low pressure gas and/or at least onemetal containing substance is used as the short-wave electromagneticradiation emitting substance.
 8. A process according to claim 1, whereinmicrowaves are used to generate said long-wave electromagneticradiation.
 9. A process according to claim 1, wherein UV rays are usedas said short-wave electromagnetic radiation.
 10. A process according toclaim 1, wherein the chemical reactions are carried out at temperaturesranging from room temperature to about 400° C.
 11. A process accordingto claim 1, wherein the chemical reactions are carried out under apressure ranging from atmospheric pressure to approximately 200 bars.12. A process for triggering and/or carrying out chemical reactions byirradiating starting materials with short-wave electromagnetic radiationemitted from at least one substance sending out short-waveelectromagnetic radiation upon irradiation and excitation with long-waveelectromagnetic radiation under operating conditions, the short-waveelectromagnetic radiation being generated in a closed vessel arrangedwithin the starting materials and containing the short-waveelectromagnetic radiation emitting substance, a low pressure gas beingused as the short-wave electromagnetic radiation emitting substance, andignition of the low pressure gas is caused by effecting an additionalirradiation and excitation of a solid electrode in the closed vesselreceiving the low pressure gas.
 13. A process according to claim 12,wherein noble gases, methane, CO₂ and gases emitting carbon bands at 193and 247 nm are used for the low pressure gas to generate the short-waveelectromagnetic radiation.
 14. A process for triggering and/or carryingout chemical reactions by irradiating starting materials with short-waveelectromagnetic radiation emitted from at least one substance sendingout short-wave electromagnetic radiation upon irradiation and excitationwith long-wave electromagnetic radiation under operating conditions, theshort-wave electromagnetic radiation being generated in a closed vesselarranged within the starting materials and containing the short-waveelectromagnetic radiation emitting substance, and metal containingsubstances which, under said operating conditions, form volatilesubstances sending out said short-wave electromagnetic radiation uponirradiation and excitation with said long-wave electromagnetic radiationbeing used as the short-wave electromagnetic radiation emittingsubstance.
 15. A process according to claim 14, wherein As, Bi, Cd, Cs,Ge, Hg, P, Pb, Rb, Sb, Se, Sn, Te, Tl or Zn are used as said metalcontaining substances.